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Metal Gear Leg Stiffeners

wood vs metal

I'll just throw this out there and see if others agree.

Seems to me the wood are true dampeners and will reduce the shimmy through absorbing the vibration. Whereas the metal stiffeners change the fundamentals of the gear leg; they make the gear stiffer fore and aft, while not doing much up and down.
 
I agree with you
The metal bar stiffens the gear leg more than the wood and encourages the gear to do more bending at the top near the motor mount...just my 0.02
 
I didn't know about or think of the metal bar a few years ago
when I mounted the gear with wood.
If now I think I would try the metal bar, if they didn't work,
remove and go wood or ?
MG
 
Up and down "damping" is not a priority with my installation, it's the fore/aft shimmy that I want to inhibit. The metal stiffeners I use are a subtle change, shimmy can still occur but it occurs with a shorter moment and I can now run more tire pressure without shimmy than I could previously.

I suspect this situation will be unique to particular airframes depending on aircraft weight, wheel/pant mass, tire pressure/balance, gear alignment and phases of the moon. What works for one aircraft may not be the ideal for another. I like the metal stiffeners because they can be easily removed or modified if desired....no fiberglass or bonding needed.
 
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Adel clamps for the stiffeners

I'm probably over thinking this, but I'd rather do that than screw it up. I recently bought an RV 9 and would like to add the stiffeners. I have read this thread several times and am curious about adel sizing. I have gone to Amazon looking for the correct ones and the sizing I am seeing has been either in inches or MM's. In this thread the numbers ginen have been like -12, -18. Are these mm's or a different calibration of sizing that I should be looking for. Thanks Gary
 
I'm probably over thinking this, but I'd rather do that than screw it up. I recently bought an RV 9 and would like to add the stiffeners. I have read this thread several times and am curious about adel sizing. I have gone to Amazon looking for the correct ones and the sizing I am seeing has been either in inches or MM's. In this thread the numbers ginen have been like -12, -18. Are these mm's or a different calibration of sizing that I should be looking for. Thanks Gary

Those are diameters in 16ths of an inch, so a -12 is 3/4”, a -16 is an inch, and so forth.
 
Well, I started my stiffeners today. I'm a pretty low level fabricator compared to most of you, but I enjoy doing what I can. I cut the aluminum and that went fine. I ordered an assortment of adel clamps from Amazon, and, I'm not comfortable with those. The holes in them are 17/64, and in my mind that is way to big to use the #10 machine screws. I thought about just cutting longer ones down and drilling my own holes but my first attempt didn't go well and the drill bit was snagging on the stainless and twisting it up. And, maybe I just need to drill with less pressure. And, I had another idea of putting the proper size grommets in the holes and using the #10 screws and that did OK, but I'm not sure that is a great idea for long term, although it does cushion the movement some which may not be all bad??? Anyways, just wanted to throw this out there and see what I get for feedback. Are there adel clamps with smaller holes, should I make my own from what I have, or is it possable that the grommets may be OK?
Thanks Gary.
 
Use carbon fibre

Make the stiffener out of carbon fibre. You can buy fibre sheet online and cut into the strips. It's much thinner and fits inside the fairings better. Lighter and works better at doing the job. I made the strips out of differnet thicknesses aluminium and had trouble getting the fairings to fit. I didn't want to remake fairings so went to carbon fiber. They do a better job and weight less as well.
Different thicknesses are available.

Steve
 
The whole idea is stiffness, not cushioning, so avoid soft things in the assembly if you can.

Carbon is a decent idea but it will need to be about as thick and wide as the aluminum. As it is, quasi-isotropic carbon has similar stiffness to aluminum, maybe 8-9 msi modulus compared to about 10 for aluminum. It is less dense, though. The lower modulus suggests that it shouldn't be thinner. Make it as wide as will fit.

I think Steve got lucky. If you can include something like a pre-formed unidirectional shape, running longways, then it can be thinner but it's probably not going to be easy to get bolts or screws reliably in it unless there's some bidirectional fibers in there.

Dave
 
... I thought about just cutting longer ones down and drilling my own holes but my first attempt didn't go well and the drill bit was snagging on the stainless and twisting it up....

Try using a step drill. Less likely to snag, I think.
But no reason you can't male your own.

Finn
 
My question was more to do with dealing with the hole in the adel clamps. I'll assume they are available with 3/16 holes and look for some different ones. In reading the thread it just mentioned getting clamps from Amazon and that was what I did, but, as usual, there was more to it. Gary
 
Uni directional

Yes, I used multiple layers of uni directional with a single layer of bid on outsides, and one layer between the uni layers. When drilling the holes, clamp some aluminium to both sides, very tightly and use a drill press for a clean hole.

Uni comes in very thin sheets and can be cut with a rotary knife, normally use for cloth fabric.
 
….. from Amazon and that was what I did, but, as usual, there was more to it. Gary

I will admit that I buy a LOT of stuff through Amazon for my shop - but very rarely does it get installed on (or in) and airplane. You can buy all sorts of metal clamps on the ‘net or at the local Ace, but unless you buy buy them as an aircraft part, they have no specification to meet…such as hole size….

ACS, B&B, WagAero, Wicks - they all list Adel clamps that meet spec.

Paul
 
Yes, I used multiple layers of uni directional with a single layer of bid on outsides, and one layer between the uni layers....

That's the way to do it. That uni is what made it work, plus any additional width you found. And the bid let you put the holes in it. Nice!

Dave
 
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